Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
-
Economics & Finance
Selected Reading
How to determine if an argument is sent to the JavaScript function?
To determine if an argument is sent to a JavaScript function, you can use several approaches including default parameters, checking for undefined, or using the arguments object.
Using Default Parameters
Default parameters provide fallback values when arguments are not passed or are undefined:
<!DOCTYPE html>
<html>
<body>
<script>
function display(arg1 = 'Tutorials', arg2 = 'Learning') {
document.write(arg1 + ' ' + arg2 + "<br>");
}
display('JavaScript', 'Programming'); // Both arguments provided
display('JavaScript'); // Only first argument
display(); // No arguments
</script>
</body>
</html>
JavaScript Programming JavaScript Learning Tutorials Learning
Checking for undefined
You can explicitly check if parameters are undefined to determine if they were passed:
<!DOCTYPE html>
<html>
<body>
<script>
function checkArguments(arg1, arg2) {
if (arg1 === undefined) {
document.write("arg1 was not provided<br>");
} else {
document.write("arg1: " + arg1 + "<br>");
}
if (arg2 === undefined) {
document.write("arg2 was not provided<br>");
} else {
document.write("arg2: " + arg2 + "<br>");
}
document.write("<br>");
}
checkArguments("Hello", "World");
checkArguments("Hello");
checkArguments();
</script>
</body>
</html>
arg1: Hello arg2: World arg1: Hello arg2 was not provided arg1 was not provided arg2 was not provided
Using arguments.length
The arguments.length property tells you exactly how many arguments were passed:
<!DOCTYPE html>
<html>
<body>
<script>
function countArguments() {
document.write("Arguments passed: " + arguments.length + "<br>");
for (let i = 0; i < arguments.length; i++) {
document.write("Argument " + i + ": " + arguments[i] + "<br>");
}
document.write("<br>");
}
countArguments("A", "B", "C");
countArguments("X");
countArguments();
</script>
</body>
</html>
Arguments passed: 3 Argument 0: A Argument 1: B Argument 2: C Arguments passed: 1 Argument 0: X Arguments passed: 0
Comparison of Methods
| Method | Use Case | Modern Approach |
|---|---|---|
| Default Parameters | Provide fallback values | Yes (ES6+) |
| undefined Check | Explicit argument validation | Yes |
| arguments.length | Count total arguments | Legacy (use rest parameters instead) |
Conclusion
Default parameters are the most modern and clean approach for handling missing arguments. Use undefined checks when you need explicit control over argument validation.
Updated on: 2026-03-15T21:49:24+05:30
158 Views
Advertisements